This invention relates to a posture measurement and feedback instrument designed to prevent the slumped or immobile sitting postures that cause dysfunction and pain such as head, neck, and back pain. Especially effected are those who sit for hours every day on a regular basis, which due to the rapid computerization of society is an ever increasing group.
In order to prevent these posture dependent ailments successfully a posture measurement and feedback instrument needs to alert users when they slump or become immobile in an inexpensive, valid, reliable, and user-friendly manner.
Cost
An informal survey of potential consumers revealed that they may be willing to spend about $200 for a personal posture feedback instrument.
Validity
Validity would require that the instrument is able to differentiate healthy from unhealthy posture. The postures identified by the literature to be most harmful for the spine are prolonged episodes of slumped sitting, heavy stoop lifting, and prolonged episodes of immobility regardless of spinal curvature. Therefore a valid posture feedback instrument needs to be able to distinguish upright sitting from slumped sitting, squat lifting from stoop lifting and mobile from immobile posture.
Reliability
Reliability would require that the posture sensorxe2x80x94body interface of the posture feedback instrument be stable enough to prevent measurement error due to displacement. The sensor should in other words not slip or come loose with the regular daily activities of the users. Nor should the posture readings be subject to variability by extraneous forces such as the earth""s magnetic field or extremity movement.
User-friendliness
A user-friendly posture feedback instrument requires that (a) it may be applied independently without much ado by a user, (b) one simple calibration of thresholds covers the entire range of postures a user goes through (e.g. alternating between sitting, standing, and lifting), (c) it does not restrict normal activities such as leaning back against a backrest, (d) it may be used inconspicuously, and (e) it is portable.
While the high prevalence of posture dependent back pain has motivated the invention of a number of posture feedback instruments designed to facilitate healthy posture, they have to this point not managed to become a common consumer item, because none of the instruments has to this point succeeded in being cost efficient, valid, reliable and user-friendly. Rather, the prior art suffers from a number of disadvantages:
(a) U.S. Pat. Nos. 5,425,378 (1995), 5,402,107 (1995), and 5,474,083 (1995) only measure body position relative to gravity and in the case of U.S. Pat. No. 5,474,083 (1995) electromyographic activity, both of which are not suited to measure the spinal curvature that differentiates erect from slumped spinal posture.
(b) U.S. Pat. Nos. 5,553,531 (1996), 4,730,625 (1988), 5,522,401 (1996), and 4,007,733 (1977) are integrated in garments, belts, or suspenders, all of which may easily slip relative to the spine or be regarded unfashionable.
(c) U.S. Pat. Nos. 5,143,088 (1992), 5,012,819 (1991), 5,398,697 (1995), and 4,527,982 (1985) are bulky or require to be worn outside the clothing, both of which precludes an inconspicuous application.
(d) Donning and doffing U.S. Pat. Nos. 5,243,998 (1993) requires a user to undress, making it user-unfriendly.
(e) The application of the sensing means of U.S. Pat. Nos. 5,400,800 (1995), 5,146,929 (1992), 5,143,088 (1992) 5,012,819 (1991), and the Spinoscope(copyright) (see copy of flyer) to the back of a user requires the help of a second person, making it user-unfriendly. Mounting the sensing means to the back also causes discomfort and displacement of the sensing means when using a back rest thus excluding an application by seated occupations.
(f) U.S. Pat. Nos. 5,400,800 (1995), 5,146,929 (1992), 5,143,088 (1992), 5,012,319 (1991), 4,660,829 (1987), 4,527,982 (1985), 5,398,697 (1995), 4,665,928 (1987), and 5,469,861 (1995) attempt to measure joint motion directly. As opposed to the indirect method of 5,433,201 (1995), where measurement is based on joint movement dependent skin dilation and contraction, the direct method requires an attachment of the sensing means to either of the articulating members of a joint. The sensing means can however only be attached to the skin which displaces relative to the articulating bones with movement. The resulting displacement of the sensing means relative to the joint causes measurement error. Tightening the attachment can only partially solve this problem and causes discomfort and soft tissue dysfunction. Furthermore, the mechanical linkages of U.S. Pat. Nos. 5,400,800 (1995), 5,146,929 (1992), 5,143,088 (1992), 5,012,819 (1991), 4,660,829 (1987), and 4,527,982 (1985) require rotation and sliding of numerous parts relative to one another. Such elaborate hardware arrangement drives up the cost, makes the instrument bulky, and causes friction which in turn reduces measurement sensitivity.
(g) The more elegant solution of U.S. Pat. No. 5,433,201 (1995) avoids all the above-mentioned disadvantages. Rather than trying to obtain a direct measure of joint motion by attaching to either joint member, U.S. Pat. No. 5,433,201 (1995) measures the amount of joint motion dependent skin dilation and contraction as is commonly done with the Schober method of the German physician Paul Schober (1865-1943). The preferred embodiment of U.S. Pat. No. 5,433,201 (1995) with ultrasonic sensing means has been marketed as xe2x80x9cOrthoSonxe2x80x9d posture trainer (see copy of flyer) at a cost of $600, definitively above what might be paid by an average consumer. Other than cost, other disadvantages of using an ultrasonic transmitter and receiver are that both need to be powered with a separate cable and that the evaluation of the signal is complicated. When the distance between two points on the skin above the spine changes with movement, the travel time of the ultrasound between the transmitter and receiver changes only minutely, requiring a very sensitive microprocessor to measure and subtract subsequent travel times. A Hall signal on the other hand is easily processed and can be fed directly into standard telemetry systems such as the one offered by the company Conrad Electronic. Developing a cost efficient, valid, reliable and user-friendly slump and immobility guard for seated occupations was part of the applicant""s doctoral work in physical therapy. This development included the testing of an alternate embodiment of U.S. Pat. No. 5,433,201: the method of measuring joint dependent skin dilation with a simpler and more cost efficient Hall sensor rather than an ultrasonic sensor. Realizing the skin dilation method of U.S. Pat. No. 5,433,201 with Hall sensor technology comprises the application of a magnet to a fist position on the skin and a Hall sensor to a second position on the skin. When choosing a user-friendly application of the magnet and the Hall sensor on the chest rather than the back, the chest""s skin with the magnet and Hall sensor on it approximates with slumping and stretches when the spine is straightened. In theory this should change the Hall reading accordingly. Upon testing however, slumping was found to not merely shorten, but to also fold the chest""s skin. Accordingly, slumping did not only approximate the magnet and the Hall sensor as the skin shortened and lengthened. Rather, the skin folding also caused a multidimensional rotation of the magnet and the Hall sensor relative to one another. The problem this created was that the approximation of the magnet and the Hall sensor changed the Hall readings one way, while at the same time the associated rotation changed the readings another way. The result was that during a continuous slumping motion, the Hall readings would often begin to reverse midway. Thus, the method of attaching the magnet and the Hall sensor separately as suggested by U.S. Pat. No. 5,433,201 did not allow for valid measures of slumping and had to be abandoned.
Other drawbacks of attaching the magnet and the Hall sensor separately as suggested in U.S. Pat. No. 5,433,201 (1995) were that:
often the magnet was lost;
the Hall sensor got no reading when the magnet was applied in too great of a distance from the Hall sensor;
the earth""s magnetic field influenced the Hall readings more than a change in posture when the magnet and the Hall sensor were mounted too far apart;
slumping caused the magnet and the Hall sensor to collide when they were mounted too close to each other;
the Hall readings increased or decreased depending on which pole of the magnet was facing the Hall sensor, which caused a misinterpretation of posture data on several occasions when by mistake the magnet was attached with reversed polarity.
(h) None of the prior art instruments above utilize common telecommunication devices such as cellular phones or pagers for posture measurement and feedback. Cellular phones and pagers are well tested mass market products already containing all the means required for posture feedback and posture data recording. Namely, these are a housing, means to attach the housing to the clothing or the dashboard of a user, a user interface, a microprocessor for signal processing and data storage, means for wireless data transmission, and means for generating acoustic, vibratory, and visual feedback. Adding the posture measurement and feedback function to cellular phones and pagers merely requires minor reprogramming of the microprocessor and a connection with a posture sensor, thus providing the cellular phone and pager user group with a very inexpensive, inconspicuous, reliable, and durable posture measurement and feedback option.
(i) None of the prior art instruments above offer computer users the option of using their computer for storage of posture data, threshold calibration, or feedback at the same time as they use another application professionally (as is common for the clock and the help function of computers). This saves the cost for extra posture data storage or feedback means.
(j) None of the prior art instruments alert users when their posture becomes to immobile.
(k) None of the prior art instruments offer a feedback option where a postural dysfunction automatically triggers a display of those exercises best suited to reverse or prevent the harmful effects of that particular postural dysfunction.
Accordingly, several objects and advantages of (a) applying the posture signal source and receiver on either half of a hinge, (b) applying the hinge to the skin, where spinal slump creates a horizontal crease across the xyphoid process, (c) using common telecommunication devices such as cellular phones or pagers for posture measurement and feedback, (d) providing the option of allowing computer users to use their regular computer to receive posture feedback or store their posture data while they use their computer for unrelated purposes, (e) providing the option of alerting users when their posture becomes too immobile, and (f) offering a feedback option where a postural dysfunction automatically triggers a display of those exercises best suited to reverse or prevent the harmful effects of that particular postural dysfunction as proposed in the present invention are as follows:
(a) The method of attaching the posture signal source and receiver on either half of a hinge and applying the hinge to a skin area that deforms in response to a defined posture change, translates the resulting multidimensional skin movement into one reliable plane of rotation around the axis of the hinge. Thus, the confounding mixture of linear and rotational motion found with the method of U.S. Pat. No. 5,433,201 (1995) where signal source and receiver are attached directly to the skin, is avoided.
Another advantage of applying the signal source and receiver to a hinge is that it allows for the signal source to rotate around the receiver in steady proximity. As opposed to the method of U.S. Pat. No. 5,433,201 (1995) where the signal source and the receiver approximate and move apart, the fixed mount and steady proximity between signal source and receiver provided by the present invention has a number of significant advantages:
The proximity between signal source and receiver greatly reduces error due to extraneous variables like, in the case of an electromagnetic sensor system, the earth""s magnetic field.
The proximity between signal source and receiver also allows for a less intensive signal, which in the preferred embodiment allows for a very small magnet to be used. A small magnet on the other hand reduces cost, weight, bulkiness, and the concern of users who believe strong magnetic fields to be a potential health risk.
The standardized range of signal intensity which results when signal source and receiver are attached to a hinge, allows for the means of signal processing to be standardized accordingly.
Mounting signal source and receiver to the hinge makes the application user-friendly, because users won""t have to worry about at which angle and distance they need to be applied.
The application becomes more reproducible and allows for a mathematical conversion of exponential electromagnetic readings into linear degrees of hinge rotation, thus allowing for a close correlation between posture data and the actual posture they represent.
(b) Applying the hinge to the skin, such that the axis of the hinge lies on the crease which appears across the xyphoid process with spinal slumping, was found to be the most effective and lest error susceptive sensor placement for the measurement of slumping as well as stoop lifting. Extensive experimental research showed that this hinge placement is most sensitive to spinal slump and stoop lifting while showing an only insignificant reaction to extraneous movements such as spinal side-bending and rotation, arm movements, respiratory excursions of the ribcage and the abdomen, or alternating between sitting and standing.
(c) Adding a posture measurement and feedback function to common telecommunication devices such as cellular phones or pagers requires only minor modifications and makes inconspicuous and cost efficient posture measurement and feedback available to the users of these devices. Rather than going through the expensive process of building and testing a posture measurement and feedback instrument from scratch, adding a posture measurement and feedback function to cellular phones and pagers allows for a lot of its thoroughly tested and mass produced components to be used. Namely, these are a micro processor, an audio feedback unit, a vibratory feedback unit, means for wireless transmission of data, an user interface, a power supply, and means to attach the instrument to the dashboard or the clothing of a user. Thus adding a posture measurement and feedback function to cellular phones and pagers merely requires a minor reprogramming of their micro processor and connecting a posture sensor. Modified in this manner, cellular phones and pagers provide an utterly inconspicuous method of posture measurement and feedback, because cellular phones and pagers have become so common no one notices them anymore.
(d) With the rapid computerization of society the number of those who sit in front of a computer for hours every day on a regular base is ever increasing. Using the regular computer of these computer users to provide them with posture feedback or to store their posture data (e.g. for posture research) while they use their computer for unrelated purposes, saves the cost for extra posture data storage or feedback means.
Another advantage is that updating personal computer software is a lot easier than reprogramming the microprocessor of a separate posture measurement and feedback instrument. Software updates for the personal computer (even very individual solutions) could for example simply be posted on a web page for download by users. Therefore the preferred embodiment of the present invention reduces the feedback unit carried by the user to the most simple and inexpensive essentials, while the more complex options of posture data storage, posture threshold calibration, and posture feedback are provided via personal computer.
(e) Providing immobility feedback enables users to avoid this harmful immobile posture behavior.
(f) A feedback option where a postural dysfunction automatically triggers a display of those exercises best suited to reverse or prevent the harmful effects of that particular postural dysfunction, allows for a most effective compensation of that particular dysfunction.
In accordance with the present invention a posture measurement and feedback instrument comprises (a) the application of the posture signal source and receiver on either half of a hinge, (b) the application of the hinge to the skin where spinal slump creates a horizontal crease across the xyphoid process, (c) adding a posture measurement and feedback function to common telecommunication devices such as cellular phones and pagers, (d) the method of using the regular computer of computer users as a means of posture measurement and feedback while they use their computer for unrelated purposes, (e) the option of alerting users when their posture becomes too immobile, and (f) the feedback option that a postural dysfunction automatically triggers the display of those exercises best suited to reverse or prevent the harmful effects of that particular postural dysfunction.